The list of edge features

node.ext

The list of extended information of node features

edge.ext

The list of extended information of edge features

infer.method

The inference method used to compute the likelihood

...

Extra parameters need by the inference method

Details

This function calculates the negative log likelihood of CRF model as well as
the gradient. This function is intended to be called by optimization algorithm
in training process.

In the training data matrix instances, each row is an instance and
each column corresponds a node in CRF.
The variables node.fea, edge.fea, node.ext, edge.ext
are lists of length equal to the number of instances, and their elements are
defined as in crf.update respectively.